This invention is concerned with the scavenging of waste anesthetic gases emitted to the ambient environment during the administration of anesthesia or analgesia (inhalation sedation) by gas inhalation.
The administration of anesthetic or analgesic (inhalation sedation) gas to dental patients involves a mask (hood) placed over the nose of the patient and the introduction of a controlled amount of gas, through the mask, to the patient. Heretofore, such gas that either has leaked from the mask perimeter or was exhaled by the patient has been allowed to dissipate into the ambient environment. Recent concerns about the danger presented by this escaping gas in the environment of an operating room or dental office, particularly the side effects on personnel who are subject to this environment on a continual basis, have prompted increased attention and approaches to the elimination of such gas escape.
In one approach, as exemplified by U.S. Pat. No. 3,877,691 to Foster, an exhaust hood, connected to a vacuum system, overlies an extended area above the patient's face. The hood in a perforated hollow manifold and is transparent to permit the attending operator or surgeon to view the patient
U.S. Pat. No. 3,271,239 to Meyers describes a suction manifold connected to the exhaust port or ports of an anesthesia system pop-off valve to capture the exhaust.
U.S. Pat. No. 4,015,598 to Brown discloses a double wall face mask being in essence, a mask over a mask. The inner mask defines a chamber over the patient's face communicating with a source of gas to be inhaled. The outer mask encloses and defines an exhaust chamber outside of the inner mask, the exhaust chamber communicating with a gas removal line. A check valve opens the facial chamber to the exhaust chamber during exhalation and the exhaust chamber is open to the surrounding atmosphere adjacent the face engaging perimeter of the inner mask to draw escaped gases from the surrounding atmosphere into the exhaust passage for disposal.